Google Reader app using tons of data?
A few days ago I was unpleasantly surprised by a thirtyfold increase in my data usage in the course of a single day. I just switched to an unlocked Nexus 5 on Ting (MVNO on Sprint's network) and you pay for what you use, so I've been monitoring my usage via their app. I was on track for a sub-$30 bill when WHAM, I jump from their Small data category (1-100MB) into their Large category (500-1000MB) because of some inexplicable 760MB of data being used by Google Books. I made an account here to document this issue for others and to show that the issue is not isolated to the Kindle app (I got here by finding a post about someone with a Note 3 using over 10 Gigs of background in 12 days thanks to Kindle).
I have zero books downloaded to my phone (in fact it is set to Wifi only), and the ENTIRE book I was reading is a PDF of only 12 MB uncompressed. I did a quick tar.gz on it and got it down to 11 MB. I could download the entire book three times in the foreground data that Reader used, and about 50 times over in the background data used. I have contacted Google about this, but I am not yet out of the "you can do X, Y, and Z to reduce your usage/disable feature Q" stage where they don't admit to there being a problem with the software/firmware. I would have written this off as a fluke until I found several reports of Kindle apps using hundreds of Megs and even Gigs of data in exactly the same way Google Reader has for me.
I highly recommend you uninstall any e-reader apps you have if you don't use them, because the Kindle app is even reported to do this without even being used! I have background data turned off now, but I'm even afraid of the suspiciously large foreground usage. Maybe I will just put my books into HD Youtube videos and stream them; it will probably use less data.
It sucks that my otherwise flawless first month on Ting is going to be forever tainted by a $15-20 higher bill due to Google. My bill will still be less than half what it was when I was on a shared family plan with Verizon, though. :)